Document Editor · JavaScript API

Character Formatting and Selections

Explore selection ranges, read character formatting and modify selected document content through the JavaScript API.

Live Selection API

Inspect the current selection

Select text in the document. The range and character attributes below follow the selection automatically.

Start0zero-based

Length0characters

End0start + length

0+0=0

Selected text Loading selection... Waiting for the editor

Character format

Font-

Size-

Text color-

Background-

Bold-

Italic-

Underline-

Strikeout-

Select a document range

Enter a zero-based start position and the number of characters to select.

Start Length

What this demonstrates

Understand ranges and common formatting

A selection identifies a document range and exposes the character attributes shared by the text in that range. The same object can inspect, select and format content.

Selection object

TXTextControl.selection

Range members

Selection.getStart / getLength

Uniform format detection

Selection.isCommonSelectionValueSelected

How it works

Selection.getStart returns the zero-based position of the first selected character. Selection.getLength returns the number of selected characters, so the end position is calculated as start + length. A length of 0 represents the text input position rather than a range of characters.

The inspector listens for inputPositionChanged and charFormatChanged. It reads the selected text and character attributes through callback-based API calls whenever the range or its formatting changes.

Before displaying a formatting value, Selection.isCommonSelectionValueSelected checks whether every selected character shares that value. Mixed fonts, colors or styles are therefore reported as Mixed instead of presenting a misleading default.